十万个为什么·科学启蒙30篇（3）
22 / 30
正在校验访问权限...
Earth’s Axis Points Toward One Star
地球轴指向一颗星，所以北极星几乎不动
-
Earth spins like a top, and its axis points steadily toward a spot near Polaris.
-
That means Polaris stays almost fixed while other stars seem to circle around it.
-
From the North Pole, it appears directly overhead; from the equator, it sits on the horizon.
-
Its position changes only very slowly over centuries due to wobble in Earth’s spin.
-
Other stars rise and set each night because Earth rotates under them constantly.
-
But Polaris stays put since it lines up with our planet’s turning center.
-
You can use it to find north when hiking or sailing at night.
-
Ancient sailors and explorers relied on it before GPS or compasses existed.
-
If you watch the sky for an hour, you’ll see stars swirling but Polaris staying still.
-
It’s not the brightest star, but it’s the most useful one for finding direction.